<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script type="text/javascript">
		var arr1=[1,2,3];
		var arr2=arr1; //引用

		arr2.push(4);

		alert(arr1);  
		alert(arr2);

		//所以最终的数据 都是1234
	</script>
</head>
<body>
	
</body>
</html>